Glycosylation-deficient hepatocyte growth factor

ABSTRACT

The invention provides a modified glycosylation-deficient HGF and a production method thereof. The glycosylation-deficient HGF is produced by introducing amino acid mutation(s) so that no glycosylation take place at at least one glycosylation site of hepatocyte growth factor.

TECHNICAL FIELD

The invention relates to a glycosylation-deficient hepatocyte growthfactor. In particular, the invention relates to hepatocyte growth factorthat is modified by deficiency of glycosylation.

BACKGROUND ART

Hepatocyte growth factor (hereinafter abbreviated as HGF) is a proteinhaving a mitogenic activity on hepatocytes. Some differences in aminoacid sequences are observed among known HGFs and HGF is also named as SF(scatter factor), TCF (tumor cytotoxic factor) and the like in additionto HGF. The known proteins having mitogenic activities on hepatocytesare collectively named as HGFs in the present invention. HGFs are knownto be physiologically active peptides that exert various pharmacologicalactions such as mitogenic action, morphogenetic action,neovascularization action, nerve protective action and anti-apoptoticaction, in addition to mitogenic activity on hepatocytes (see non-patentdocument 1: Matsumoto, K. et al., Kidney International, 2001, vol. 59,p2023-2038).

From its pharmacological actions, HGF is expected to be developed astherapeutic agents for cirrhosis, therapeutic agents for renal diseases,epithelial cell proliferation promoters, anti-cancer agents, preventiveagents for side effects in cancer therapy, therapeutic agents for lunginjury, therapeutic agents for gastroduodenal injuries, therapeuticagents for cerebral neuropathy, preventive agents for immunosuppressionside effects, collagen degradation promoters, therapeutic agents forcartilage injury, therapeutic agents for artery diseases, therapeuticagents for pulmonary fibrosis, therapeutic agents for hepatic diseases,therapeutic agents for blood coagulation malfunction, therapeutic agentsfor plasma hypoproteinemia, therapeutic agent for wounds, neuropathyimproving agents, hematopoietic stem cell increasing agents and hairrestoration promoters (for example, see patent documents 1 to 14:JP-A-4-18028, JP-A-4-49246, EP-492614-A, JP-A-6-25010, WO93/8821,JP-A-6-172207, JP-A-7-89869, JP-A-6-40934, WO94/2165, JP-A-6-40935,JP-A-6-56692, JP-A-7-41429, WO93/3061 and JP-A-5-213721).

HGF is secreted from organs such as liver, brain, lung, bone marrow,spleen, placenta and kidney, or from blood cells such as platelets andleukocytes. However, since HGF is present in the body in a minutequantity, it is necessary to produce HGF in a large scale using cells bygenetic engineering techniques in order to use it as medicalpreparations. It has been known that HGF can be produced using animalcells such as Chinese hamster ovary (CHO) cells (see, for example,patent documents 15 and 16: JP-11-4696-A and JP-10-191991-A).

However, the method for producing proteins using animal cells such asCHO cells is expensive, resulting in increase of drug prices.

As a method for producing a recombinant protein at a low cost,expression of proteins in prokaryotic cells such as E. coli byintroducing genes of interest into them has been known (see non-patentdocument 2: Swarts, J. R., Current Opinion in Biotechnology, 2001, vol.12, p195-201). However, there exists a problem that no glycosylationoccurs in recombinant proteins produced in the prokaryotic cells such asE. coli. This is because the prokaryotic cells such as E. coli do notcontain endoplasmic reticulum and Golgi apparatus that are places forbiosynthesis of sugar chain(s).

Addition of a sugar chain to a protein and its modification in an animalcell is post-translational modifications using no template, differingfrom the case of biosynthesis of DNAs or proteins. Thispost-translational modification is performed by a complicated mechanismmediated by various glycosylation-related enzymes locally present inintracellular organelle called endoplasmic reticulum and Golgiapparatus. That is, a sugar chain is elongated so as to obtain a givensugar chain structure when sequential addition and cleavage ofmonosaccharides occur according to a complicated biosynthetic pathwaycatalyzed by enzymes specific to certain linkages of monosaccharides(glycosidase and glycosyltransferase) (see non-patent document 3:Kornfeld, R., et. al, Annual Review of Biochemistry, 1985, vol. 54,p631-664).

Sugar chain(s) added to proteins in this way have been known to bedeeply involved in whole life phenomena of higher organisms (seenon-patent documents 4 and 5: Kobata, A., European Journal ofBiochemistry, 1992, vol. 209, p483-501; Varki, A., Glycobiology, 1993,vol. 3, p97-130).

It has been known that half or more of proteins in the human body existas glycoproteins to which sugar chains are added (see non-patentdocument 6: Goochee, C. F. et al., Biotechnology, vol. 9, p1347-1355).

If a glycoprotein originally present in the form carrying sugar chainsis converted into a form containing no sugar chain, there is a fear oflosing activity. For example, it is known that erythropoietin, known asa hematopoietic hormone, lose its activity when the sugar chains areremoved (see non-patent document 7: Takeuchi, M. et al., Glycobiology,1991, vol. 1, p337-346).

Yeast is known as a host cell that is capable of producing a recombinantprotein at low cost and has a glycosylation ability (see non-patentdocuments 8: Wiseman, A., Endeavor, 1996, vol. 20, p130-132; non-patentdocument 9: Russell, C. et al., Australian Journal of Biotechnology,1991, vol. 5, p48-55; non-patent document 10: Buckholz, R. G. et al,Biotechnology, 1991, vol. 9, p1067-1072). Since yeast is a eukaryoticcell and has endoplasmic reticulum and Golgi apparatus, it isconsequently equipped with glycosylation mechanism. However, since theglycosylation mechanism of yeast differs significantly from that ofanimal cells, when a protein having glycosylation site(s) is produced inyeast, sugar chain(s) of yeast type would be added. It is known that thesugar chain structures of yeast are significantly different from thoseof human and other mammals (see non-patent document 11: Germmill, T. R.et al., Biochemica et Biophysica Acta, 1999, vol. 1426, p227-237).

Accordingly, such recombinant proteins cannot be used for medicines forhuman beings and other mammals because they exhibit antigenicity againsthuman and mammals.

Further, an insect cell is also a host having a glycosylation abilityand can produce a protein at relatively low cost, however, the sugarchain structures of an insect cell are also different from those ofhuman type (see non-patent document 12: Altmann, F. et al.,Glycocomjugate Journal, 1999, vol. 16, p109-123).

Accordingly, there is a possibility for a recombinant protein derivedfrom insect cells to show antigenicity against human and other mammals.

Then, one can envisage production of a protein containing no sugarchains by removing sugar chains from a protein produced using yeast,insect cells, or the like, or by introducing a gene designed to havemutation(s) at glycosylation sites in a protein molecule into yeast,insect cells, or the like. However, if a protein originally present inthe form carrying sugar chains is converted into a protein containing nosugar chain, there is a fear of losing activity, as described above.

Five sugar chains are added to HGF (see non-patent documents 13: Hara,H. et al., Journal of Biochemistry, 1993, vol. 114, p76-82; non-patentdocuments 14: Shimizu, N, et. al, Biochemical and Biophysical ResearchCommunications, 1992, vol. 189, p1329-1335). With respect to theinfluence of removing the sugar chains of HGF on the activity, it isreported that, when HGF-producing cells were cultured in the presence oftunicamycin, an inhibitor of N-glycosylation, secreted HGF maintainedthe motogenic activity (see non-patent document 15; Hofmann, R. et al.,Biochemica et Biophysica Acta, 1992, vol. 1120, p343-350. HFG is denotedas SF in the report).

However, this report does not give sufficient information since theextent of deficiency of the sugar chains in the HGF produced in thepresence of tunicamycin was not analysed.

The report described that HGF maintained motogenic activity aftertreatment of the HGF with N-glycanase or O-glycanase, however, thereport showed that HGF treated with N-glycanase or O-glycanase adsorbedonto a ConA column that recognizes sugar chains. The fact that HGFtreated with N-glycanase or O-glycanase adsorbed onto a ConA columnmeans that the removal of the sugar chains was limited. Therefore, thedescriptions that the HGF treated with N-glycanase or O-glycanasemaintained motogenic activity does not lead to a conclusion thatglycosylation-deficient HGF maintains motogenic activity.

HGF has a variety of activities, including mitogenic activity,morphogenetic activity, neovascularization activity, anti-apoptopticactivity and nerve protective activity in addition to the motogenicactivity (see non-patent document 16: Matsumoto, K. et al., Biochemicaland Biophysical Research Communications, 1997, vol. 239, p639-644).

It cannot be always concluded that functions of HGF other than motogenicactivity are maintained even if glycosylation-deficient HGF retains themotogenic activity. For example, NK2 that is a truncated variant of HGFhas motogenic activity, whereas it has no mitogenic activity (seenon-patent document 17: Hartmann, G. et al., Proceedings of NationalAcademy of Science of the United States of America, 1992, vol. 89,p11574-11578).

As can be seen from the above, it was unclear at all how many of thediverse functions are maintained in non-glycosylated HGF. HGF has beenconsidered to be a repair factor of organs because of its diverseactivities, and it could not be concluded that highly complicatedfunctions are not affected by deficiency of sugar chains in HGFmolecules.

DISCLOSURE OF THE INVENTION

The objects of the present invention are to provide aglycosylation-deficient hepatocyte growth factor in which sugar chainsare allowed to be lacking, and to provide a method for producing thesame.

The inventors of the present invention have found, through intensivestudies on the function of the sugar chain to solve the problems above,that the functions of HGF are maintained even if the sugar chains of HGFare removed. It was quite unexpected that HGF, a highly functionalprotein, could maintain its function even if the sugar chains areremoved. Moreover, it was an astonishing discovery that stability ofglycosylation-deficient HGF in the blood circulation was improved ascompared with glycosylated HGF. The inventors have completed theinvention through advanced studies based on the findings describedabove.

The invention provides:

(1) a glycosylation-deficient hepatocyte growth factor lacking the sugarchains at all or at least one of the glycosylation sites of hepatocytegrowth factor;

(2) the glycosylation-deficient hepatocyte growth factor according tothe above (1), wherein a mutation is introduced into an amino acidsequence so that no glycosylation occurs at at least one ofglycosylation sites of the hepatocyte growth factor;

(3) the glycosylation-deficient hepatocyte growth factor according tothe above (2), wherein at least one of the following modifications of(a) to (d) are applied to the amino acid sequence of the hepatocytegrowth factor:

(a) Asn in at least one of consensus sequences for N-glycosylationrepresented by Asn-X-Ser or Asn-X-Thr (X represents an amino acid exceptPro), which exist in the amino acid sequence of hepatocyte growthfactor, is substituted by another amino acid residue;

(b) Ser or Thr in one consensus sequence, or Ser and/or Thr in two ormore consensus sequences for N-glycosylation represented by Asn-X-Ser orAsn-X-Thr (X represents an amino acid except Pro), which exist in theamino acid sequence of hepatocyte growth factor, is/are substituted byother amino acid residue(s),

(c) X in at least one of consensus sequences for N-glycosylationrepresented by Asn-X-Ser or Asn-X-Thr (X represents an amino acid exceptPro), which exist in the amino acid sequence of hepatocyte growthfactor, is substituted by Pro, or

(d) at least one of Ser and/or Thr that undergo/undergoesO-glycosylation, which exist in the amino acid sequence of hepatocytegrowth factor, is/are substituted by other amino acid residue(s);

(4) the glycosylation-deficient hepatocyte growth factor according toany one of the above (1) to (3), wherein the hepatocyte growth factor ishuman hepatocyte growth factor;

(5) the glycosylation-deficient hepatocyte growth factor according toany one of the above (1) to (3), wherein the hepatocyte growth factor isfeline or canine hepatocyte growth factor;

(6) the glycosylation-deficient hepatocyte growth factor according toany one of the above (1) to (4), which is modified based on the aminoacid sequence of SEQ ID NO: 1, wherein at least one of modificationsrepresented by (a) to (e) below is applied to the amino acid in SEQ IDNO: 1:

(a) substitution of amino acid 294 and/or 296 by another amino acid,and/or substitution of amino acid 295 by Pro, leading thereby to noglycosylation of the amino acid 294;

(b) substitution of amino acid 402 and/or 404 by another amino acid,and/or substitution of amino acid 403 by Pro, leading thereby to noglycosylation of the amino acid 402;

(c) substitution of amino acid 476 by another amino acid, resulting inno glycosylation of the amino acid 476;

(d) substitution of amino acid 566 and/or 568 by another amino acid,and/or substitution of amino acid 567 by Pro, leading thereby to noglycosylation of the amino acid 566; or

(e) substitution of amino acid 653 and/or 655 by another amino acid,and/or substitution of amino acid 654 by Pro, leading thereby to noglycosylation of the amino acid 653;

(7) the glycosylation-deficient hepatocyte growth factor according toany one of the above (1) to (4), which is modified based on the aminoacid sequence of SEQ ID NO: 2, wherein at least one of modificationsrepresented by (a) to (e) below is applied to the amino acid in SEQ IDNO: 2:

(a) substitution of amino acid 289 and/or 291 by another amino acid,and/or substitution of amino acid 290 by Pro, leading thereby to noglycosylation of the amino acid 289;

(b) substitution of amino acid 397 and/or 399 by another amino acid,and/or substitution of amino acid 398 by Pro, leading thereby to noglycosylation of the amino acid 397;

(c) substitution of amino acid 471 by another amino acid, leadingthereby to no glycosylation of the amino acid 471;

(d) substitution of amino acid 561 and/or 563 by another amino acid,and/or substitution of amino acid 562 by Pro, leading thereby to noglycosylation of the amino acid 561; or

(e) substitution of amino acid 648 and/or 650 by another amino acid,and/or substitution of amino acid 649 by Pro, leading thereby to noglycosylation of the amino acid 648;

(8) a DNA comprising a base sequence encoding theglycosylation-deficient hepatocyte growth factor according to any one ofthe above (1) to (7);

(9) a vector integrated with the DNA according to the above (8);

(10) a method for producing the glycosylation-deficient hepatocytegrowth factor according to any one of the above (1) to (7) comprisingthe steps of: introducing the vector according to the above (9) into acell; culturing the cell; producing a glycosylation-deficient hepatocytegrowth factor in the cell or into the cell culture medium; andrecovering and purifying the glycosylation-deficient hepatocyte growthfactor from the cell or from the cell culture medium;

(11) the method according to the above (10) for producing theglycosylation-deficient hepatocyte growth factor, wherein the cell is aeukaryotic cell;

(12) the method according to the above (11) for producing theglycosylation-deficient hepatocyte growth factor, wherein the eukaryoticcell is a yeast or an insect cell;

(13) a method for producing the glycosylation-deficient hepatocytegrowth factor according to any one of the above (1) to (7), comprisingthe steps of: introducing the vector according to the above (9) into aninsect individual, allowing the insect individual to produce theglycosylation-deficient hepatocyte growth factor, and recovering andpurifying the glycosylation-deficient hepatocyte growth factor from theinsect individual;

(14) a method for producing the glycosylation-deficient hepatocytegrowth factor according to any one of the above (1) to (7), comprisingthe steps of: removing the sugar chain(s) wholly or partially bytreating hepatocyte growth factor having sugar chain(s) with an enzyme,and recovering and purifying the glycosylation-deficient hepatocytegrowth factor from the enzyme reaction solution;

(15) a method for producing the glycosylation-deficient hepatocytegrowth factor according to any one of the above (1) to (7), comprisingthe steps of: introducing a vector integrated with a DNA containing abase sequence encoding hepatocyte growth factor having sugar chain(s) orthe vector according to the above (9) into a cell having noglycosylation ability; culturing the cell; allowing the cell to producea glycosylation-deficient hepatocyte growth factor in the cell or intothe cell culture medium; and recovering and purifying theglycosylation-deficient hepatocyte growth factor from the cell or cellculture medium;

(16) a method for producing the glycosylation-deficient hepatocytegrowth factor according to any one of the above (1) to (7), comprisingthe steps of: synthesizing the glycosylation-deficient hepatocyte growthfactor by a cell-free protein synthesis system using a gene comprising abase sequence encoding hepatocyte growth factor having sugar chain(s) orthe base sequence according to the above (8) as a template, andrecovering and purifying the glycosylation-deficient hepatocyte growthfactor from the reaction solution;

(17) a pharmaceutical preparation comprising the glycosylation-deficienthepatocyte growth factor according to any one of the above (1) to (7) asan active ingredient; and

(18) a gene therapy agent containing the DNA according to the above (8).

The glycosylation-deficient HGF of the present invention hascharacteristics identical to HGF having sugar chains with respect tomitogenic, motogenic and morphogenetic activities, and heat stability.Therefore, it can be used as a substitute for glycosylated HGF.Accordingly, the pharmaceutical preparation comprising theglycosylation-deficient HGF of the present invention as an activeingredient can be used similarly to glycosylated HGF, i.e., astherapeutic agents for cirrhosis, therapeutic agents for renal diseases,epithelial cell proliferation promoters, anti-cancer agents, preventiveagents for side effects in cancer therapy, therapeutic agents for lunginjury, therapeutic agents for gastroduodenal injuries, therapeuticagents for cerebral neuropathy, preventive agents for immunosuppressionside effect, collagen decomposition promoters, therapeutic agents forcartilage injury, therapeutic agents for artery diseases, therapeuticagents for pulmonary fibrosis, therapeutic agents for hepatic diseases,therapeutic agents for blood coagulation malfunction, therapeutic agentsfor plasma hypoproteinemia, therapeutic agent for wound, neuropathyimproving agents, hematopoietic cell increasing agents and hairrestoration promoters for mammals (such as human, dog, cat, rat, mouse,rabbit, horse, cattle, sheep and guinea pig).

Medicines containing the DNA encoding the glycosylation-deficient HGF ofthe present invention can be also used as a gene therapy agent for thediseases as described above.

Since the glycosylation-deficient HGF of the invention is more stable inthe blood circulation than glycosylated HGF, the dosage of HGF can bereduced to prevent the side effect of HGF.

The glycosylation-deficient HGF of the invention can be produced at lowcost since it can be produced in yeast and insect cells.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 shows the results of SDS-PAGE analysis of each HGF. Reducedsamples of HGFs were electrophoresed and the gel was subjectd to silverstaining.

FIG. 2 shows a graph of mitogenic activity of HGFs on hepatocytes, wherethe activity is indicated in terms of DNA synthesis of rat hepatocytes.

FIG. 3 shows motogenic activity of HGFs, where the activities werecompared based on the degree of scattering of MDCK cells.

FIG. 4 shows motogenic activity of HGFs, where the activities werecompared based on the degree of tube formation of MDCK cells.

FIG. 5 shows thermal stability of HGFS. Each HGF was incubated at 37° C.for the days indicated. The remaining activity was expressed as relativeactivity based on the amount of DNA synthesis of rat hepatocytes.

FIG. 6 shows stability of HGFs in the blood circulation.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail below.

The glycosylation-deficient HGF of the present invention refers to HGFthat is modified so as to lack sugar chain(s) at the whole or at leastone of the glycosylation sites of HGF having sugar chains derived frommammals such as human, dog, cat, rat, mouse, rabbit, horse, cattle,sheep and guinea pig.

Furthermore, the glycosylation-deficient HGF of the present inventionincludes proteins having an amino acid sequence in which a mutation isintroduced so that the known HGFs do not undergo glycosylation, whereinone or several amino acids are deleted, substituted, added or inserted,and having an HGF activity. In addition, the glycosylation-deficient HGFof the present invention also includes proteins having a homology of atleast about 60% or more, preferably about 80% or more, more preferablyabout 90% or more, and furthermore preferably about 95% or more with theamino acid sequence in which a mutation is introduced so that noglycosylation takes places in the known HGFs, and having an HGFactivity.

The phrase “one or several amino acids are deleted, substituted, addedor inserted” with respect to the amino acid sequence refers to deletion,substitution, addition or insertion of amino acid(s) of a number, one toseveral, which can be introduced by well-known technological methodssuch as a site-directed mutagenesis method or can be introducednaturally.

The term “homology” with respect to the amino acid sequence as describedabove refers to the degree of identity of amino acid residuesconstituting each sequence as a result of comparison of primarystructures of proteins.

The glycosylation-deficient HGF of the invention can be obtained byintroducing a vector, to which a mutation is introduced so that noglycosylation occurs at at least one site of the glycosylation sites ofthe HGF, into cells.

The glycosylation-deficient HGF of the invention may also be obtained byintroducing a vector containing a base sequence of HGF havingglycosylation sites into a cell with no glycosylation ability.

As the method of introducing mutation(s) into an HGF gene so as toprevent addition of sugar chain(s) at at least one of glycosylationsites of HGF, it is advantageous to introduce mutation(s) into a basesequence corresponding to the amino acid sequence of a glycosylationsite to be deficient. Since the sugar chain attached to a proteinincludes an N-linked type and an O-linked type, the following mutationsare introduced into a base sequence, respectively.

Consensus sequence for the attachment of N-linked sugar chains have beenknown (Asn-X-Ser or Asn-X-Thr; X represents an amino acid other thanproline). When the consensus sequence exists, a sugar chain is added toAsn in the consensus sequence (Kobata A., Eur. J. Biochem., 1992, vol.209, p. 483-501). Accordingly, an N-linked type sugar chain can be madedeficient by introducing mutation(s) into a base sequence so as toconvert Asn in the consensus sequence into another amino acid (forexample Gln), or to convert Ser or Thr in the consensus sequence intoanother amino acid (for example Gly or Ala). In this case, it ispreferable to appropriately select an amino acid for conversion so asnot to form a new consensus sequence with backward and forward aminoacids of the above-mentioned consensus sequence. It may also bepermissible to introduce mutation(s) into a base sequence so thatproline is introduced at X site in a consensus sequence.

In the case of an O-linked type sugar chain, a sugar chain is added to ahydroxyl group of Ser or Thr in an O-glycosylation site, however, aconsensus sequence for O-glycosylation does not exist. A sugar chain atthe O-glycosylation site can be made deficient by introducingmutation(s) into a base sequence so as to convert Ser or Thr subjectedto O-glycosylation into another amino acid (for example, Gly and thelike). In this case, it is preferable to appropriately select an aminoacid for conversion so as not to form the above-described consensussequence for N-linked sugar chains with backward and forward amino acidsequences of the replaced amino acid.

The glycosylation sites, for example in the human HGF, are Asn atposition 294 (N-linked type sugar chain), Asn at position 402 (N-linkedtype sugar chain), Thr at position 476 (O-linked type sugar chain), Asnat position 566 (N-linked type sugar chain) and Asn at position 653(N-linked type sugar chain) of the amino acid sequence of SEQ ID NO: 1in the sequence listing. The glycosylation sites in the 5 aminoacids-deficient human HGF of SEQ ID NO: 2 in the sequence listing areAsn at position 289 (N-linked type sugar chain), Asn at position 379(N-linked type sugar chain), Thr at position 471 (O-linked type sugarchain), Asn at position 561 (N-linked type sugar chain) and Asn atposition 648 (N-linked type sugar chain).

The consensus sequence for N-linked sugar chains in the case of thehuman HGF is present at positions 294 to 296, positions 402 to 404,positions 566 to 568 and positions 653 to 655 of the amino acid sequenceof SEQ ID NO: 1 in the sequence listing. The consensus sequence in thecase of the 5-amino acids-deleted type human HGF is present at positions289 to 291, positions 397 to 399, positions 561 to 563 and positions 648to 650 of the amino acid sequence in SEQ ID NO: 2 in the sequencelisting.

Introduction of mutation(s) into a base sequence of HGF can be conductedusing a known technology such as the Kunkel method with syntheticmutagenic primers corresponding to a portion into which mutations are tobe introduced. By using a commercially available mutagenesis kit and thelike, mutations can be introduced easily.

A recombinant expression vector for glycosylation-deficient HGF can beconstructed from a recombinant vector such as a plasmid and a phage,which contains DNA coding an amino acid sequence ofglycosylation-deficient HGF or DNA coding the amino acid sequence of HGFhaving sugar chain(s), by excising this DNA with a restriction enzyme,and re-connecting it to downstream of a promoter within a vectorsuitable for expression of the glycosylation-deficient HGF by using arestriction enzyme and DNA ligase. More specifically, the vector isconstructed so that it contains, if necessary, (1) promoter, (2)ribosome binding site, (3) initiation codon, (4) DNA containing a basesequence coding a glycosylation-deficient HGF of the present invention,(5) termination codon and (6) terminator in this order toward downstreamdirection of transcription.

The above-mentioned DNA includes not only DNA composed of a basesequence coding a glycosylation-deficient HGF that can be obtained byintroducing mutation(s) into the above-mentioned glycosylation site(s),but also (a) DNA having a base sequence having deletion, substitution,addition or insertion of one or more bases in the base sequence codingthe above-mentioned glycosylation-deficient HGF having an HGF activity,(b) DNA hybridizable under stringent conditions with DNA that iscomposed of a base sequence complimentary to DNA having a base sequencecoding the above-mentioned glycosylation-deficient HGF having an HGFactivity, or (c) DNA having a homology of at least 60% or more with DNAhaving a base sequence coding the above-mentionedglycosylation-deficient HGF having an HGF activity.

The phrase “deletion, substitution, addition or insertion of one toseveral bases” with respect to the base sequence above refers todeletion, substitution, addition or insertion of bases of a number 1 toseveral, which can be introduced by well-known technological methodssuch as a site-directed mutagenesis method or can be introducednaturally.

DNA hybridizable under stringent conditions means a DNA that can beobtained by a colony hybridization method, plaque hybridization methodor southern blot hybridization method using the above DNA as a probe.

The stringent conditions mean hybridization conditions, for example,where hybridization is performed in SSC solution of about 0.1 to 2-foldconcentration (SSC solution at 1-fold concentration contains 150 mMsodium chloride and 15 mM sodium citrate) at a temperature of about 65°C.

DNA having homology means DNA showing a homology of at least about 60%or more under high stringent conditions, preferably DNA having ahomology of about 80% or more, more preferably DNA having a homology ofabout 90% or more, and furthermore preferably DNA having a homology ofabout 95% or more. The high stringent conditions include, for example, asodium concentration of about 19 to 40 mM, preferably about 19 to 20 mM,and a temperature of about 50 to 70° C., preferably about 60 to 65° C.Particularly, a sodium concentration of about 19 mM and a temperature ofabout 65° C. are the most preferable conditions.

As the vectors which can be used in the present invention, plasmids suchas pBR 322, pUC18, pUC19 (Toyobo Co. Ltd.) can be used when Escherichiacoli is used as a host, plasmids such as pUB110 (Sigma) can be used whenBacillus subtilis is used as a host, and plasmids such as pYES2(Invitrogen), pRB15 (ATCC 37062) can be used when yeast is used as ahost. As the expression vector for animal cells, listed are pCAGGS andpCXN2 (Niwa H., Yamamura K. and Miyazaki J., Gene, 1991, vol. 108, p.193 to 200, JP-A-03-168087), pcDL-SRα (Takebe Y., et al., Mol. Cell.Biol., 1988, vol. 8, p. 466-472) and the like. Additionally,bacteriophages λgt10, λgt11 (Stratagene), and a vector derived from agene of SV40 (BRL), BPV (ATCC VR-703), retrovirus and the like arelisted, however, there is no specific restriction so long as they arevectors capable of replicating and amplifying in a host.

Also regarding promoters and terminators, there is no specificrestriction so long as they work in a host that is used for expressionof a base sequence coding a glycosylation-deficient HGF. As thepromoters, listed are trp promoter, lac promoter, recA promoter, λPLpromoter, lpp promoter and the like when Escherichia coli is used as ahost, and listed are PHO5 promoter, PGK promoter, GAP promoter, ADHpromoter and the like when yeast is used as a host. When animal cellsare used as a host, promoters obtained from virus genomes such as Roussarcoma virus (virus RSV), MPSV, polyoma virus, fowlpox virus,adenovirus, bovine papilloma virus, fowl sarcoma virus, cytomegalovirus(CMV), hepatitis B virus, simian virus 40 (SV40), and vaccinia virus;metallothioneine promoter; heat shock promoter; and the like are listed.In the case of using a higher mammal host, an enhancer is preferablyintroduced into a vector. By introducing an enhancer, transcriptionincreases. Listed as the enhancers are SV40 enhancer, initialpromoter/enhancer of cytomegalovirus, polyoma enhancer, adenovirusenhancer and the like. As the terminator, listed are trp terminator, lppterminator and the like when Escherichia coli is used as a host, listedare amyF terminator and the like when Bacillus subtilis is used as ahost, listed are CYC1 terminator and the like when yeast is used as ahost, and listed are SV40 terminator, HSV1TK terminator and the likewhen animal cells are used as a host. These promoters and terminatorsare appropriately combined depending on the host used.

An expression vector for a glycosylation-deficient HGF is introducedinto a host by a competent cell method (J. Mol. Biol., 1970, vol. 53, p.154), protoplast method (Proc. Natl. Acad. Sci. USA, 1978, vol. 75, p.1929), calcium phosphate method (Science, 1983, vol. 221, p. 551), DEAEdextran method (Science, 1982, vol. 215, p. 166), electric pulse method(Proc. Natl. Acad. Sci. USA, 1984, vol. 81, p. 7161), in vitro packagingmethod (Proc. Nat. Acad. Sci. USA, 1975, vol. 72, p. 581), virus vectormethod (Cell, 1984, vol. 37, p. 1053), micro injection method (Exp.Cell. Res., 1984, vol. 153, p. 347) and the like, to produce atransformant.

The cell which can be used as a host is not particularly restricted, andcells derived from animals, plants, insects, and eukaryoticmicroorganisms, and prokaryotic microorganisms, and the like are listed.These cells may form an individual, and animal individuals, plantindividuals and insect individuals may be used as a host. The animalcell may be an adherent cell or floating cell, and may be a cellproducing and accumulating a glycosylation-deficient HGF in the cell, ormay be a cell producing and secreting a glycosylation-deficient HGF outof the cell. As the animal cells, for example, CHO cell (Chinese hamsterovary cell), COS cell, BHK cell, mouse C127 cell and Hela cell and thelike are listed. As the plant cells, for example, cells of rice,tobacco, Arabidopsis thaliana and the like are listed, and as the insectcell, for example, cells of Sf9, Sf21 and the like are listed. As theinsect individual, for example, silk worm (Bombyx mori) is mentioned. Asthe prokaryotic microorganisms, Escherichia coli, Bacillus subtilis andthe like are listed. As the eukaryotic microorganisms, yeasts such asSaccharomyces cerevisiae, Schizosaccharomyces pombe, Candida boidinii,Pichia pastoris and the like, and filamentous fungi such as Aspergillus,Trichoderma, Mucor and the like are listed. Among these, yeast, insectcell or living insect is preferable. Since the cells of the prokaryoticmicroorganism have no glycosylation ability, an wild-type HGF genehaving glycosylation site(s) may be introduced into the cell.

The resultant transformant is cultured in an appropriate mediumdepending on its host for the purpose of producing an intendedglycosylation-deficient HGF. The medium contains carbon sources,nitrogen sources, inorganic substances, vitamins, serum and medicamentsand the like necessary for growth of the transformant. As the medium, LBmedium (Nissui Pharmaceutical Co., Ltd.), M9 medium (J. Exp. Mol.Genet., Cold Spring Laboratory, New York, 1972, p. 431) and the like arelisted when the host of a transformant is Escherichia coli, and YEPDmedium (Genetic Engineering, vol. 1, Plenum Press, New York, 1979, p.117) and the like are listed when the host is yeast. When the host is ananimal cell, a modified Eagle medium (MEM medium) containing about 20%or less of fatal calf serum, Dulbecco's modified Eagle medium (DMEMmedium) or RPM1640 medium (Nissui Pharmaceutical Co., Ltd.) and the likeare listed. Culturing of a transformant is conducted usually at atemperature of 20 to 45° C. and pH of 5 to 8, and ventilation andstirring are conducted as required. When the host is an animal adherentcell and the like, carriers such as glass beads, collagen beads andacetyl cellulose hollow fibers are used. Culturing of a transformant canbe conducted even with a medium composition or under culturingconditions other than the above compositions and conditions so long asthe transformant can grow, therefore, the composition and culturingcondition are not limited to the above-mentioned examples.

The glycosylation-deficient HGF thus produced in the culture supernatantof a transformant or in the transformant can be separated and purifiedby a combination of known methods such as salting out method, solventprecipitation method, dialysis method, ultrafiltration method, gelelectrophoresis method, gel filtration chromatography, ion exchangechromatography, reverse phase chromatography, affinity chromatographyand the like. Particularly, combinations of a salting out method usingammonium sulfate, S-sepharose ion chromatography, heparin sepharoseaffinity chromatography and phenylsepharose reverse chromatography, orcombinations of a salting out method using ammonium sulfate, S-sepharoseion chromatography and anti-HGF antibody sepharose affinitychromatography are preferable and effective purification methods.

The glycosylation-deficient HGF of the present invention can also beprepared by obtaining glycosylated HGF by conventionally known methods,and subsequently by treating the HGF with an enzyme that can removesugar chains. As the enzymes that can remove sugar chains,glycopeptidase F, glycopeptidase A and the like can be used for thepurpose of removing an N-linked type sugar chain. Removal of an O-linkedtype sugar chain can be attained by a combination of sialidase,fucosidase and O-glycanase. The HGF from which a sugar chain is removedby enzymatic treatment can be collected as the glycosylation-deficientHGF of the present invention and purified by the above-mentionedpurification method.

Further, the glycosylation-deficient HGF of the present invention can beobtained also by utilizing cell-free protein synthesis system. Thecell-free protein synthesis system means a method of performing proteinsynthesis using DNA or mRNA coding the intended protein as a templatenot using a live cell, but using a cell extract that is prepared fromEscherichia coli, rabbit reticulocyte, wheat germ and the like, or usingprotein synthesis factors derived from the cell extract solution. Sincethe cell extract solution contains molecules necessary for proteinsynthesis such as ribosome, tRNA, and translation factor, a protein issynthesized upon addition of an energy source such as ATP, GTP, etc. andamino acids as substrates. Instead of cell extract solution, a mixtureof protein synthesis factors contained in cell extract solution may beused. In the cell-free protein synthesis system, aglycosylation-deficient HGF can be produced using, as a template, DNA ormRNA coding an HGF having glycosylation site(s), because an endoplasmicreticulum and Golgi apparatus are not contained therein. DNA or mRNAhaving mutation(s) introduced into glycosylation site(s) can also beused. The glycosylation-deficient HGF synthesized in the reactionsolution of the cell-free protein synthesis system can be purified bythe purification methods as described above.

The glycosylation-deficient HGF of the present invention obtained asdescribed above has an activity equivalent to that of the glycosylatedHGF with respect to mitogenic activity, motogenic activity andmorphogenestic activity, and also has a heat stability equivalent tothat of the glycosylated HGF. In addition, the glycosylation-deficientHGF of the present invention is more stable in the blood circulationthan the glycosylated HGF.

The glycosylation-deficient HGF of the invention can be applied to humanbeings as well as to mammals (for example dog, cat, rat, mouse, rabbit,hose, cattle, sheep and guinea pig).

The medicine containing the glycosylation-deficient HGF of the inventionmay be used, like the wild type. glycosylated HGF, for therapeuticagents for cirrhosis, therapeutic agents for renal diseases, epithelialcell proliferation promoters, anti-cancer agents, preventive agents ofside effects in cancer therapy, therapeutic agents for lung injury,therapeutic agents for gastroduodenal injuries, therapeutic agents forcerebral neuropathy, preventive agents for immunosuppression sideeffect, collagen degradation promoters, therapeutic agents for cartilageinjury, therapeutic agents for artery diseases, therapeutic agents forpulmonary fibrosis, therapeutic agents for hepatic diseases, therapeuticagents for blood coagulation malfunction, therapeutic agents for plasmahypoproteinemia, therapeutic agent for wound, neuropathy improvingagents, hematopoietic cell increasing agents and hair restorationpromoters. The medicine containing DNAs encoding theglycosylation-deficient HGF of the present invention may be also usedfor therapeutic agents of the diseases as described above.

The glycosylation-deficient HGF of the present invention is effective asa drug, and used in the form of general pharmaceutical preparation. Thepharmaceutical preparation containing the glycosylation-deficient HGF ofthe present invention as an active ingredient can adopt various dosageforms (for example, liquid, solid, capsule and the like), and ingeneral, the glycosylation-deficient HGF as an active ingredient is usedin combination with a conventional carrier or a binder to give aninjection, inhalant, suppository or oral agent, and an injection issuitable. This injection can be prepared by a normal method, and forexample, can be prepared by dissolving a glycosylation-deficient HGF anda binder into a suitable solvent (for example, sterile purified water,buffer solution, physiological saline solution and the like), filteringthe solution through a filter and the like for sterilization, and thenfilling this in a sterile vessel. The amount of theglycosylation-deficient HGF in an injection is usually adjusted fromabout 0.0002 to 3 (w/v %), preferably from 0.001 to 2 (w/v %). The oraldrug is formulated into a dosage form such as, for example, tablet,granule, fine granule, powder, soft or hard capsule, liquid, emulsion,suspension, syrup and the like, and these preparations can be preparedby an ordinary method for preparation. The suppository can also beprepared by an ordinary method for preparation using a conventional base(for example, cacao butter, lauric butter, glycerogelatine, Macrogol,Witepsol and the like). The inhalant can also be prepared according tonormal means for preparation. The amount of the glycosylation-deficientHGF in a preparation can be appropriately adjusted depending on dosageform, disease to be treated and the like.

In the formulation of a pharmaceutical preparation of theglycosylation-deficient HGF of the present invention, a stabilizer ispreferably added. As the stabilizer, for example, albumin, globulin,gelatin, alanine, glycine, mannitol, glucose, dextran, sorbitol,ethylene glycol and the like are exemplified. The pharmaceuticalpreparation of the present invention may contain other necessaryadditives, for example, solvents (for example, physiological salinesolution, sterile purified water, injectable water and the like),excipients (for example, fructose, D-sorbitol, glucose, starch,crystalline cellulose, dextrin and the like), binders (for example,gelatin, corn starch, tragacanth, gum arabic and the like), solubilizers(for example, lauromacrogol, Polysorbate 80, polyoxyethylene hardenedcastor oil 60, gum arabic, sodium benzoate and the like), antioxidants(for example, L-ascorbic acid, tocopherol, sodium edetate and the like),soothing agents (for example, benzalkonium chloride, procainehydrochloride and the like), isotonic agents (for example, sodiumchloride, glucose, D-mannitol, glycerin and the like), buffers (forexample, citric acid, sodium citrate, acetic acid, sodium acetate,lactic acid, sodium hydrogenphosphate and the like), thickening agents(gum arabic, carmellose, popidone, methylcellulose and the like),preservatives (for example, methyl p-oxybenzoate, ethyl p-oxybenzoate,propyl p-oxybenzoate, chlorobutanol, benzyl alcohol, benzalkoniumchloride and the like), pH adjusters (hydrochloric acid, sodiumhydroxide, citric acid, acetic acid and the like), and the like.

In the case of liquid preparation, it is preferable to retain thepreparation by cryopreservation, or by lyophilization and the like toremove moisture. In the case of a lyophilized preparation, injectabledistilled water and the like are added before its use to redissolve thepreparation.

In the case of oral preparation, it is preferable to apply a film of anenteric coating agent (for example, cellulose acetate phthalate,methacrylic acid copolymer, hydroxypropylcellulose phthalate,carboxymethylethyl cellulose and the like) to make a granule, tablet andthe like, and in the case of capsule, an enteric coated capsule ispreferable.

The preparation of the present invention can be administered via asuitable administration route depending on its dosage form. For example,it can be made into a form of injection and administered intravenously,intraarterially, subcutaneously, or intramuscularly, etc. The dosethereof is appropriately adjusted depending on disease, symptom, age,body weight and the like of a patient, and for example, it is usuallyfrom 0.01 mg to 500 mg, preferably from 0.05 mg to 100 mg in adults inthe case of a glycosylation-deficient HGF, and once to several timesadministrations per day are suitable.

The DNA having a base sequence encoding the glycosylation-deficient HGFof the present invention is integrated into the vector, and is used as agene therapy agent.

The gene therapy agent of the invention is preferably prepared as acomplex of the glycosylation-deficient HGF gene and a gene carrier.Preferable gene carriers are virus vectors or cationic gene carriers.Examples of the virus vector include mouse leukemia virus vector,adenovirus vector, adeno-associated virus vector, HIV vector, herpessimplex vector, Sendai virus vector or the like. Examples of thecationic gene carrier include substances having an affinity with thegene, such as polyamino acids (e.g. polylysine, polydiamnobutyric acid,etc.) and cationic synthetic polymers (e.g. liposome, ethyleneimine,etc.).

The present invention will be further illustrated in detail by thefollowing examples, but the invention is by no means restricted to theseExamples.

Abbreviations used in the Examples have the following meanings:

HGF: hepatocyte growth factor

dHGF: 5 amino acids-deleted type hepatocyte growth factor

LB medium: Luria-Bertani medium

DMEM medium: Dulbecco's modified Eagle medium

Amp: ampicillin

FCS: fatal calf serum

NaCl: sodium chloride

BSA: bovine serum albumin

PBS: phosphate buffered saline

Tween 80: polyoxyethylene(20)sorbitan monooleate

EXAMPLE 1

A base sequence encoding 5 amino acids-deleted type HGF (dHGF, alsonamed as wild type dHGF) represented by SEQ ID NO: 3 of the sequencelisting was integrated into pCAGGS vector. The vector obtained(hereinafter referred to as a wild type vector) is named as pCAGGS-dHGF.

For the purpose of introducing mutations to 5 glycosylation sites(positions 289, 397, 471, 561 and 648 of SEQ ID NO: 2 in the sequencelisting) present in dHGF protein, five mutagenic primers(5′-phosphorylated) shown in Table 1 were synthesized, and site-directedmutagenesis was performed using the pCAGGS-dHGF vector as a template. Bythis mutagenesis, Asn 289, Asn 397, Asn 561 and Asn 648 are substitutedby Gln, and Thr 471 is substituted by Gly, in the amino acid sequencerepresented by SEQ ID NO: 2. TABLE 1 Sequence Primer listing 5′-tgc gctgac aat act atg caa gac act SEQ ID NO:4 gat gtt cct ttg-3′ 5′-ggc aaaaat tat atg ggc cag tta tcc SEQ ID NO:5 caa aca aga tct gg-3′ 5′-tgc aaacag gtt ctc caa gtt tcc cag SEQ ID NO:6 ctg gta tat gg-3′ 5′-ggg aag gtgact ctg caa gag tct gaa SEQ ID NO:7 ata tgt gct gg-3′ 5′-ggt gat acc acacct gga ata gtc aat SEQ ID NO:8 tta gac cat cc-3′

QuickChange Multi Kit manufactured by Stratagene Co. was used for themutagenesis. The vector containing the introduced mutations (hereinafterreferred to as a mutated vector) was transformed into a competent cellof E. coli XL10 Gold, and Amp-resistant colonies were picked up on anLB/Amp plate. Plasmids were extracted from each clone obtained, and theintended clone was screened by analyzing a base sequence on the regioncoding the glycosylation-deficient HGF. A vector in which intended fivemutations and no other mutation were confirmed was selected and used inthe subsequent experiments. The mutated vector obtained is referred toas pCAGGS-dHGF-NG. The same operation was performed using threemutagenic primers of primer 1, primer 2 and primer 3, and a mutatedvector pCAGGS-dHGF-αNG designed so as to lack three sugar chains of theα-chain was prepared. The same operation was also performed using themutagenic primers 3 and 4, and a mutated vector pCAGGS-dHGF-βPNGdesigned so as to lack two sugar chains of the β-chain was prepared.

Subsequently, the wild type vector pCAGGS-dHGF and the mutated vectorspCAGGS-dHGF-NG, pCAGGS-dHGF-αNG and pCAGGS-dHGF-βNG were transfected toCOS-7 cells, respectively. The COS-7 cells were cultured in a DMEMmedium supplemented with 10% fetal calf serum (FCS). The culture mediumof the cell was replaced with serum-free DMEM medium just beforetransfection. Transfection was carried out by a lipofection method usinglipofectamin 2000 (manufactured by Invitrogen). The culture medium wasreplaced with DMEM containing 1% FCS 6 hours after the transfection, andheparin was added at a concentration of 1 μg/mL. Culturing was continuedfor 3 days in order to accumulate wild type dHGF orglycosylation-deficient dHGF in the culture medium. The culture mediawere collected 3 days after the cultivation and mixed, and the mixedmedium was. filtered through a 0.22 μm filter. The filtrate waspreserved at −80° C. until purification. The concentrations of the wildtype dHGF and glycosylation-deficient dHGFs secreted into the culturemedium were analyzed by ELISA.

The above culture medium was thawed and, after filtration through a 0.22μm filter, the filtrate was applied onto a HiTrap Heparin column (bedvolume: 5 mL, manufactured by Amersham Biosciences) equilibrated with 50mM Tris-HCl (pH 7.5), 0.01% Tween 80 and 0.3M NaCl at a flow rate of 0.6mL/minute. The column was washed with 50 mM of Tris-HCl (pH 7.5), 0.01%Tween 80 and 0.3M NaCl, and the wild type dHGF andglycosylation-deficient dHGF were eluted by increasing the NaClconcentration to 2 M. The elution was conducted at a flow rate of 1mL/minute, and the eluate was fractionated into tubes (2.5 mL/tube).Fractions containing the wild type dHGF or glycosylation-deficient dHGFwere collected, and the buffer solution was exchanged by ultrafiltrationwith a buffer solution containing 50 mM Tris-HCl (pH 7.5), 0.01% Tween80 and 0.3M NaCl. The fraction was applied onto a Mini S column (bedvolume 0.8 mL, manufactured by Amersham Biosciences) at a flow rate of0.4 mL/minute. After washing the column with 50 mM Tris-HCl (pH 7.5),0.01% Tween 80 and 0.3 M NaCl, the wild type dHGF andglycosylation-deficient dHGFs were eluted by increasing the NaClconcentration to 1 M. The elution was performed at a flow rate of 0.4mL/minute, and 0.4 mL each of the eluate was collected in respectivetubes. The fractions containing the wild type dHGF orglycosylation-deficient dHGFs were collected, and the extent ofpurification was confirmed by SDS-PAGE.

The dHGF obtained by introducing the wild type vector is referred to asCOS-dHGF-WT, and the glycosylation-deficient dHGFs obtained byintroducing mutated vectors are referred to as COS-dHGF-NG, COS-dHGF-αNGand COS-dHGF-βNG, respectively.

The dHGF protein was also prepared using CHO cells according to themethod described in JP-A-10-191991 (referred to as CHO-dHGF-WT).

The comparative results of SDS-PAGE for dHGFs andglycosylation-deficient dHGFs are shown in FIG. 1. It was confirmed thatthe bands of α-chain and β-chain of COS-dHGF-NG of theglycosylation-deficient dHGF were shifted respectively to positionscorresponding to the molecular weights of the peptides in which thesugar-chains are deleted. While it was observed that COS-dHGF-WT has asmaller degree of glycosylation than CHO-dHGF-WT from the comparisonbetween COS-dHGF-WT and CHO-dHGF-WT that are glycosylated (wild type)dHGFs, this may be a result from the difference of glycosylation abilitybetween COS cells and CHO cells that were used as hosts, or from thedifference of purification methods. It was confirmed that the band ofα-chain of COS-dHGF-αNG, in which only the sugar chains of the α-chainwere deleted, was shifted to a position corresponding to the lack ofsugar chain in the α-chain. It was also confirmed that the band ofβ-chain of COS-dHGF-βNG, in which only the sugar chains of the β-chainwere deleted, was shifted to a position corresponding to the lack ofsugar chain in the β-chain.

EXAMPLE 2

The mitogenic activities against rat hepatocytes of the wild type dHGFand glycosylation-deficient dHGFs obtained in Example 1 were measured.

Rat hepatocytes were separated from SD rat (age 8 weeks, male) using acollagenase perfusion method. The obtained hepatocytes were suspended ina William's E(WE) medium containing 5% FCS, and was seeded on a cultureplate at a cell density of 30,000 cells/cm². The culture medium wasremoved 4 hours later, and was replaced with 480 μL of fresh WE medium(containing 5% FCS) to continue the culturing. After additional 20hours, 20 μL of a sample solution containing the wild type dHGF orglycosylation-deficient dHGF was added to the medium to further continuethe culturing. Twenty hours after the addition of the wild type dHGF orglycosylation-deficient dHGF, [³H]-thymidine (25 Ci/mmol) was added at aconcentration of 2.5 μCi/mL, and the culturing was continued foradditional 6 hours. Thereafter, the cells were washed with PBS twice,followed by incubation with 10% trichloroacetic acid at 4° C. for 20minutes. Further, the solution was replaced with fresh 10%trichloroacetic acid and the cells were kept for 10 minutes. After thecells were washed with 1 mL of H₂O, the cells were solubilized byincubation with 0.5 N NaOH solution at 37° C. for 30 minutes. The celllysate was neutralized by adding 1 N HCl. The neutralized solution wastreated with a cell harvester to collect cell-derived substances on aglass filter. After drying the filter, a solid scintillator (MeltiLex)was placed on the filter and the filter was heated on a hot plate. Afterthe scintillator melted into the filter, radioactivity was measured witha β-counter (FIG. 2). The level of the radioactivity represents theamount of [³H]-thymidine incorporated into the cell, indicating theamount of DNA synthesis accompanying cell proliferation. In other words,the level of the radioactivity reflects the mitogenic activity.

The glycosylation-deficient dHGF (COS-dHGF-NG) showed a mitogenicactivity equivalent to that of the wild type dHGF (COS-dHGF-WT andCHO-dHGF-WT). The COS-dHGF-αNG that lacks the sugar chain of α-chain andCOS-dHGF-βNG that lacks the sugar chain of β-chain also showed similaractivities.

EXAMPLE 3

MDCK-3B cells were suspended in DMEM (containing 10% FCS), and wereseeded on a 24-well plate at a cell density of 10⁴ cells/well (480μL/well). A test sample (20 μL) containing the wild type dHGF orglycosylation-deficient dHGF was added to each well. The plate wasincubated at 37° C. for 20 hours, and the extent of scatterring wasobserved with a microscope (FIG. 3).

The glycosylation-deficient dHGF (COS-dHGF-NG) showed a motogenicactivity equivalent to that of the wild type dHGF (COS-dHGF-WT andCHO-dHGF-WT). The COS-dHGF-αNG that lacks the sugar chain of α-chain andCOS-dHGF-βNG that lacks the sugar chain of β-chain also showed similaractivities.

EXAMPLE 4

MDCK-3B cells were suspended in a collagen solution (Cellmatrix I-A,manufactured by Nitta Gelatin) dissolved in DMEM (containing 10% FCS) toprepare a solution with a cell density of 5,000 cells/mL. This solution(500 μL each) was added onto a 24-well plate (2,500 cells/well). Aftergelling collagen by incubating at 37° C. for 10 minutes, 480 μL of DMEM(containing 10% FCS) was laid on the gel, and 20 μL of a test samplecontaining the wild type dHGF or glycosylation-deficient dHGF was addedto the well. After culturing at 37° C. for 6 days, tube formation in thegel was observed with a microscope (FIG. 4).

The glycosylation-deficient DHGF (COS-dHGF-NG) showed the samemorphogenic activity as the wild type dHGFs (COS-dHGF-WT andCHO-dHGF-WT). The COS-dHGF-αNG that lacks the sugar chain of α-chain andCOS-dHGF-βNG that lacks the sugar chain of β-chain also showed similaractivities.

EXAMPLE 5

Samples of the wild type dHGFs and glycosylation-deficient dHGFs werediluted and adjusted to a concentration of 50 μg/mL with a buffersolution containing 50 mM Tris-HCl (pH7.5), 0.01% Tween 80 and 0.3 MNaCl, and were incubated at 37° C. for 7 days in sealed vessels.Aliquots of the sample solutions were collected everyday, and eachfraction was preserved at −80° C. The remaining activities of the wildtype dHGFs and glycosylation-deficient dHGFs in each sampled solutionwere evaluated by measuring the amount of DNA synthesis of hepatocytesin a similar manner to Example 2. For measuring the activity, thesampled solution was diluted to a concentration of 125 ng/mL with PBScontaining 0.5% BSA, and 20 μL aliquot of the diluted solution was addedto 480 μL of a culture medium of hepatocytes to give a finalconcentration of 5 ng/mL.

The glycosylation-deficient DHGF (COS-dHGF-NG) showed temperaturestability similar to that of the wild type dHGF (COS-dHGF-WT andCHO-dHGF-WT) (FIG. 5). The COS-dHGF-αNG that lacks the sugar chain ofα-chain and COS-dHGF-βNG that lacks the sugar chain of β-chain alsoshowed similar stabilities.

EXAMPLE 6

Na¹²⁵I (50 μCi) was added to 80 μL of a buffer solution containing 50 mMof Tris-HCl (pH 7.5), 0.01% of Tween 80 and 0.3M NaCl, and one bread ofIODO-BEADS (manufactured by Pierce) was added to the solution, followedby incubation at room temperature for 5 minutes. A solution (20 μL)containing the wild type dHGF (5 μL) or glycosylation-deficient dHGF ina buffer containing 50 mM Tris-HCl (pH 7.5), 0.01% Tween 80 and 0.3 MNaCl was added to the solution above, and the dHGFs were iodinated byincubating at room temperature for 5 minutes. The iodination reactionwas stopped by taking the reaction solution out of the tube, and thereaction solution taken out was subjected to gel filtration through aSephadex G-25 column (available from Amersham Biosciences) to purify¹²⁵I-dHGF by separating from unreacted Na¹²⁵I.

¹²⁵I-dHGF with a radioactivity of 500,000 cpm was diluted with PBScontaining 0.1% BSA to obtain a 100 μL solution. This solution wasinjected into the tail vein of ICR mouse (age 8 weeks, male). The bloodwas sampled at 1, 5, 15, 30, 60 and 120 minutes after the injection. Theplasma was separated from the collected blood, and stability of the wildtype dHGF and glycosylation-deficient dHGF in the blood circulation wasevaluated by measuring the radioactivity using a gamma counter (FIG. 6).

Stability of the glycosylation-deficient dHGF (COS-dHGF-NG) in the bloodcirculation was improved compared with that of CHO-dHGF-WT. TheCOS-dHGF-WT showed an intermediate stability between COS-dHGF-NG andCHO-dHGF-WT. This may be ascribed to the fact that the sugar chain ofthe COS-dHGF-WT is partially deficient as shown in Example 1.

INDUSTRIAL APPLICABILITY

The glycosylation-deficient HGF of the present invention is useful as asubstitute of glycosylated HGF.

1. A glycosylation-deficient hepatocyte growth factor lacking the sugarchain(s) at all or at least one of the glycosylation sites of hepatocytegrowth factor.
 2. The glycosylation-deficient hepatocyte growth factoraccording to claim 1, wherein a mutation is introduced into an aminoacid sequence so that no glycosylation occurs at at least one of theglycosylation sites of the hepatocyte growth factor.
 3. Theglycosylation-deficient hepatocyte growth factor according to claim 2,wherein at least one of the following modifications of (a) to (d) areapplied to the amino acid sequence of the hepatocyte growth factor: (a)Asn in at least one of consensus sequences for N-glycosylationrepresented by Asn-X-Ser or Asn-X-Thr (X represents an amino acid exceptPro), which exist in the amino acid sequence of hepatocyte growthfactor, is substituted by another amino acid residue; (b) Ser or Thr inone consensus sequence, or Ser and/or Thr in two or more consensussequences for N-glycosylation represented by Asn-X-Ser or Asn-X-Thr (Xrepresents an amino acid except Pro), which exist in the amino acidsequence of hepatocyte growth factor, is/are substituted by other aminoacid residue(s), (c) X in at least one of consensus sequences forN-glycosylation represented by Asn-X-Ser or Asn-X-Thr (X represents anamino acid except Pro), which exist in the amino acid sequence ofhepatocyte growth factor, is substituted by Pro, or (d) at least one ofSer and/or Thr that undergo/undergoes O-glycosylation, which exist inthe amino acid sequence of hepatocyte growth factor, is/are substitutedby other amino acid residue(s).
 4. The glycosylation-deficienthepatocyte growth factor according to claim 1, wherein the hepatocytegrowth factor is human hepatocyte growth factor.
 5. Theglycosylation-deficient hepatocyte growth factor according to claim 1,wherein the hepatocyte growth factor is feline or canine hepatocytegrowth factor.
 6. The glycosylation-deficient hepatocyte growth factoraccording to claim 1, which is modified based on the amino acid sequenceof SEQ ID NO: 1, wherein at least one of modifications represented by(a) to (e) below is applied to the amino acid in SEQ ID NO: 1: (a)substitution of amino acid 294 and/or 296 by another amino acid, and/orsubstitution of amino acid 295 by Pro, leading thereby to noglycosylation of the amino acid 294; (b) substitution of amino acid 402and/or 404 by another amino acid, and/or substitution of amino acid 403by Pro, leading thereby to no glycosylation of the amino acid 402; (c)substitution of amino acid 476 by another amino acid, resulting in noglycosylation of the amino acid 476; (d) substitution of amino acid 566and/or 568 by another amino acid, and/or substitution of amino acid 567by Pro, leading thereby to no glycosylation of the amino acid 566; or(e) substitution of amino acid 653 and/or 655 by another amino acid,and/or substitution of amino acid 654 by Pro, leading thereby to noglycosylation of the amino acid
 653. 7. The glycosylation-deficienthepatocyte growth factor according to claim 1, which is modified basedon the amino acid sequence of SEQ ID NO: 2, wherein at least one ofmodifications represented by (a) to (e) below is applied to the aminoacid in SEQ ID NO: 2: (a) substitution of amino acid 289 and/or 291 byanother amino acid, and/or substitution of amino acid 290 by Pro,leading thereby to no glycosylation of the amino acid 289; (b)substitution of amino acid 397 and/or 399 by another amino acid, and/orsubstitution of amino acid 398 by Pro, leading thereby to noglycosylation of the amino acid 397; (c) substitution of amino acid 471by another amino acid, leading thereby to no glycosylation of the aminoacid 471; (d) substitution of amino acid 561 and/or 563 by another aminoacid, and/or substitution of amino acid 562 by Pro, leading thereby tono glycosylation of the amino acid 561; or (e) substitution of aminoacid 648 and/or 650 by another amino acid, and/or substitution of aminoacid 649 by Pro, leading thereby to no glycosylation of the amino acid648;
 8. A DNA comprising a base sequence encoding theglycosylation-deficient hepatocyte growth factor according claim
 1. 9. Avector integrated with the DNA according to claim
 8. 10. A method forproducing the glycosylation-deficient hepatocyte growth factor accordingto claim 1 comprising the steps of: introducing a vector integrated witha DNA comprising a base sequence encoding the glycosylation-deficienthepatocyte growth factor according to claim 1 into a cell; culturing thecell; producing a glycosylation-deficient hepatocyte growth factor inthe cell or into the cell culture medium; and recovering and purifyingthe glycosylation-deficient hepatocyte growth factor from the cell orfrom the cell culture medium.
 11. The method according to claim 10 forproducing the glycosylation-deficient hepatocyte growth factor, whereinthe cell is a eukaryotic cell.
 12. The method according to claim 11 forproducing the glycosylation-deficient hepatocyte growth factor, whereinthe eukaryotic cell is a yeast or an insect cell.
 13. A method forproducing the glycosylation-deficient hepatocyte growth factor accordingto claim 1, comprising the steps of: introducing a vector integratedwith a DNA comprising a base sequence encoding theglycosylation-deficient hepatocyte growth factor according to claim 1into an insect individual, allowing the insect individual to produce theglycosylation-deficient hepatocyte growth factor, and recovering andpurifying the glycosylation-deficient hepatocyte growth factor from theinsect individual.
 14. A method for producing theglycosylation-deficient hepatocyte growth factor according to claim 1,comprising the steps of: removing the sugar chain(s) wholly or partiallyby treating hepatocyte growth factor having sugar chain(s) with anenzyme, and recovering and purifying the glycosylation-deficienthepatocyte growth factor from the enzyme reaction solution.
 15. A methodfor producing the glycosylation-deficient hepatocyte growth factoraccording to claim 1, comprising the steps of: introducing a vectorintegrated with a DNA containing a base sequence encoding hepatocytegrowth factor having sugar chain(s) or a vector integrated with a DNAcomprising a base sequence encoding the glycosylation-deficienthepatocyte growth factor according to claim 1 into a cell having noglycosylation ability; culturing the cell; allowing the cell to producea glycosylation-deficient hepatocyte growth factor in the cell or intothe cell culture medium; and recovering and purifying theglycosylation-deficient hepatocyte growth factor from the cell or cellculture medium.
 16. A method for producing the glycosylation-deficienthepatocyte growth factor according to claim 1, comprising the steps of:synthesizing the glycosylation-deficient hepatocyte growth factor by acell-free protein synthesis system using a gene comprising a basesequence encoding hepatocyte growth factor having sugar chain(s) or abase sequence encoding the glycosylation-deficient hepatocyte growthfactor according to claim 1 as a template and recovering and purifyingthe glycosylation-deficient hepatocyte growth factor from the reactionsolution.
 17. A pharmaceutical preparation comprising theglycosylation-deficient hepatocyte growth factor according to claim 1 asan active ingredient.
 18. A gene therapy agent containing the DNAaccording to claim 8.